Load Reduction of a Water-Entry Vehicle’s Nose Buffer Assembly: Effects of Multiple Foam Parameters

Abstract

Structural damage and functional failure pose significant challenges in water-entry engineering, often necessitating load reduction measures to ensure the vehicle’s structural integrity. The head buffer assembly is a widely adopted load reduction method, valued for its effectiveness and straightforward working principle. In this study, a numerical simulation model is established using the arbitrary Lagrangian-Eulerian (ALE) method. After experimental validation, the load reduction performance of buffer foams with varying geometric and density parameters is investigated, and an optimization strategy is proposed based on the analysis results. The research finds that increasing the length of the buffer foam within a certain range enhances load reduction. However, excessively long foam leads to fracture at the cap root, which degrades the load reduction effectiveness. The load reduction effect first increases and then decreases with the increase of truncation distance, indicating an optimal value. Density grading of the buffer foam improves load reduction performance, with a positive density gradient foam outperforming a negative density gradient one. Based on the S-curve, the feasible regions for foams of different densities are fitted to determine the optimal density under various conditions.

Keywords

Water-entry vehicle / Load characteristics / Load reduction performance / Buffer cap / Foam parameters

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